The overall objectives of the proposed research are: (1) purify and identify the enterotoxin produced by the phage group II strains of staphylococci: (2) determine the physicochemical properties of the enterotoxin; (3) prepare specific antibodies to it; (4) compare the structure around the cystine loop to that of the other enterotoxins; and (5) supply other investigators with the necessary reagents to carry on their research in this field. Identification of the enterotoxin produced by phage group II staphylococcus strains will be accomplished by relating the toxic fractions (as determined by monkey feeding tests) obtained during purification to antibodies prepared to the partially purified toxin. The enterotoxin will be purifed by chromatography on carboxymethyl-cellulose, gel filtration using the Sephadexes and isoelectric focusing. The isoelectric point, molecular weight and amino acid composition of the purified enterotoxin will be determined by conventional methods. The tryptic peptides composing the cystine loop area will be separated by chromatography and sequenced by the Edman degradation method. Specific antibodies to the new enterotoxins will be prepared by methods developed in our laboratories using New Zealand white rabbits. We plan to resume supplying other investigators with enterotoxin reagents (as we have in the past) because many worthwhile projects would not have been possible and will not in the future without our help.